Mirror bracket

ABSTRACT

A system for determining the position of vehicles in an automated warehouse of the type utilizing transfer vehicles and robot vehicles is disclosed. The position determining system includes a photo-electric sensor flexibly coupled to a robot vehicle, which sensor is responsive to its alignment with a pallet stored in the warehouse. The system further includes a photo-electric reflector retaining bracket mounted adjacent to an aisle in the warehouse, the bracket supporting a number of reflectors arranged in a pattern containing information identifying the aisle. A photo-electric transceiver supported by a mounting bracket is connected to a transfer vehicle and is arranged to provide an output signal related to the pattern of the reflectors when the transceiver is in alignment with the reflectors whereby the transfer vehicle is apprised of its location in the warehouse. The system also includes an activation reflector having a smaller reflective expanse than the pattern forming reflectors, the activation reflector being used to activate the pattern responsive portion of the transceiver. The system further includes a pair of fine alignment photo-electric transceivers which serve to finely align the transfer vehicle by requiring the vehicle to search for a position in which the two fine alignment transceivers are simultaneously aligned with a reflector supported by the retaining bracket.

This is a division of application Ser. No. 890,219, filed Mar. 27, 1978,now U.S. Pat. No. 4,218,616.

This abstract is not to be taken either as a complete exposition or as alimitation of the present invention, however, the full nature and extentof the invention being discernible only by reference to and from theentire disclosure.

BACKGROUND OF THE INVENTION

This invention relates to an automated storage and retrieval system andmore particularly to such a system including a vehicle positiondetermining system.

Automated storage and retrieval systems of the type presently known inthe art are generally rack structures which include a plurality of lanesand a number of aisles which extend orthogonally from each lane. Itemsbeing stored in the rack, such as loaded pallets, are positioned in theaisles. To retrieve a loaded pallet from a position within an aisle orto deposit a loaded pallet therein, it is necessary for a vehicle,commonly referred to as a transfer robot, to enter the aisle. Becausetransfer robots are expensive it has been found advantageous to have asingle transfer robot service a number of the aisles which extend from alane rather than to provide a robot for each aisle. To carry the singlerobot between the various aisles a vehicle commonly referred to as atransfer vehicle, which moves along the lane, is provided.

The use of such transfer vehicles and transfer robots has contributedgreatly to the efficiency and economy of modern automated warehouses.Their use has, however, required the development of systems which arecapable of apprising such robots and vehicles of their location withinthe storage system. Clearly, it is necessary that an unloaded transferrobot be aware of the fact that it is underneath the loaded palletnearest the lane in an aisle so that the robot may retrieve such palletand carry it to the transfer vehicle, which vehicle will then carry theloaded pallet and the transfer robot to a pick-up area. Similarly, it isnecessary that the transfer robot, when carrying a loaded pallet, beaware of its arrival at a position proximate the pallet nearest the lanein an aisle so that the transfer robot may deposit its loaded pallet atthat point. It is also necessary, of course, that the transfer vehicle,when carrying a transfer robot (with or without a loaded pallet), beaware of its position in a lane so that the transfer vehicle may stopand off-load the transfer robot at the proper aisle along the lane.

A number of different systems have been developed to provide therequired position information to the transfer robot and to the transfervehicle. For example, U.S. Pat. No. 3,973,685 discloses a system whereintransfer robots are provided with photo-electric sensors extending foreand aft thereof, so that the robots are apprised of their adjacency tothe pallet in the aisle nearest to the junction of the aisle and thelane as the transfer robots arrive at such point of adjacency. Suchphoto-electric sensor systems, although operating satisfactorily inideal environments, are frequently less than completely satisfactory inactual factory environments. This is due to the fact that substantialarticles, such as, for example, pieces of lumber, frequently dangle orextend from the pallets and even portions of the load carried by thepallets themselves frequently dangle or extend therefrom. Such articlesdangling or extending from the pallets form obstructions which, whenstruck by the sensors mounted on the transfer robots, frequently causethe misalignment of such sensor systems resulting in a decrease in theaccuracy of the position information provided and even damage suchsystems to the extent that they become inoperative.

Numerous attempts have also been made to provide a system whereby thetransfer vehicle is apprised of its position along a lane relative toeach of the aisles extending therefrom. One such system incorporates aplurality of photo-electric sensors mounted on the transfer vehicle anda number of pieces of reflective adhesive tape adhered to stanchions orposts adjacent to each of the aisles. The pieces of tape are arranged ina pattern or code containing information identifying the aisle adjacentto which they are positioned. Such systems, although of value, are lessthan completely satisfactory for a number of reasons. For example, in atypical warehouse environment, the reflective tape quickly loses asubstantial portion of its reflective capability due to grime coatingthe tape. Clearly, such a circumstance is intolerable in that a loss ofreflectivity of a particular piece of the tape will cause thephoto-electric system to "read" an incorrect position code. Anotherproblem arises when it is desired to alter the positions of the variouspieces of tape forming the code in that each piece of tape, once adheredto a surface, loses a substantial portion of its adhesive capabilitywhen removal and re-adhesion of the tape is attempted. Finally, the useof such reflective tape is less than completely satisfactory because thephoto-electric sensing system frequently becomes slightly misaligned dueto the vibration thereof which is caused by the movement of the transfervehicle along an aisle. Inasmuch as the angle at which light isreflected from the reflective tape surface is equal to the angle ofincidence, that is, the angle at which light is received by the tape,any misalignment of the photo-electric transmitter is magnified by thereflectivity of the tape. It is therefore clear that such a system willwork less than completely satisfactorily in the event that light fromthe photo-electric cell is transmitted other than perpendicularlyrelative to the reflective surface of the tape.

SUMMARY OF THE INVENTION

It is, therefore, an important object of the instant invention toprovide a vehicle position determining system for an automated warehouseby means of which the aforesaid drawbacks and disadvantages may be mostefficaciously avoided.

It is a further object of the invention to provide such a system wherebymisalignment of, or damage to, sensors mounted on a robot may beavoided.

It is still a further object of the instant invention to provide meansfor flexibly mounting a position detecting sensor on a robot in anautomated storage and retrieval system.

It is yet another object of the instant invention to provide anelectro-magnetic wave reflecting system for vehicle positiondetermination in an automated warehouse which is characterized byimproved reflectivity.

It is still another object of the instant invention to provide such animproved electro-magnetic wave reflection system which compensates formisalignment of the electro-magnetic wave transmission system.

It is yet a further object of the instant invention to provide anelectro-magnetic wave reflecting system for vehicle positiondetermination in an automated warehouse whereby position informationcontained in said wave reflecting system can readily be varied.

Generally speaking, the objectives of the instant invention are attainedby the provision of a vehicle position determining system comprising avehicle arranged for movement along a path, sensor means coupled to thevehicle and arranged to respond to the alignment of the sensor meanswith a pre-selected article, and means flexibly coupling the sensormeans to the vehicle.

The objectives of the present invention are also attained by theprovision of a vehicle position determining system comprising a vehiclearranged for movement along a path, an electro-magnetic wave reflectorretaining member, one or more electro-magnetic wave reflectors supportedby the retaining member, the reflectors arranged in a locationinformation containing pattern, and electro-magnetic wave transceivermeans, one of the retaining member and the transceiver means beingcoupled to the vehicle and the other being fixedly positioned wherebythe transceiver means and the retaining member are arranged for relativemovement into and out of alignment with one another, the transceivermeans being adapted to provide an output signal related to the patternupon the alignment of the transceiver means and the reflectors.

The objectives of the present invention are further attained by theprovision of a reflector retaining bracket comprising a longitudinallyextending rear wall, first and second side walls, the side walls beingspaced from one another and extending perpendicularly from a surface ofthe rear wall, and first and second pluralities of fingers, each of thefirst and second pluralities of fingers extending perpendicularly from acorresponding one of the first and second side walls and toward oneanother, the rear and side walls and the pluralities of fingers forminga channel adapted to maintain a plurality of reflectors therein, each ofthe fingers being adapted to be folded inwardly toward the rear wall forpreventing the longitudinal movement, toward the folded fingers, of areflector positioned in that portion of the channel aligned with thefingers next adjacent to the folded finger.

The objectives of the present invention are also attained by theprovision of an electro-magnetic wave transmission mounting bracketcomprising a plate having first and second pluralities of aperturesformed therein, each aperture of the first plurality corresponding to anaperture of the second plurality, the plate adapted to support aplurality of discrete electro-magnetic wave transceivers each of whichtransceivers includes a lens and an alignment pin spaced therefrom,which pin extends parallel to the axis of transmission of the lens, eachaperture of the first plurality of apertures adapted to be aligned withthe lens of one of the plurality of discrete transceivers and to passelectro-magnetic waves transmitted by the discrete transceiver andelectro-magnetic waves transmitted to the discrete transceiver, and thecorresponding aperture of the second plurality of apertures adapted toreceive the alignment pin of the one discrete transceiver, therebyaligning the one transceiver relative to the plate.

The foregoing and other objects and features of the present inventionwill be more clearly understood from the following detailed descriptionthereof, when read in conjunction with the accompanying drawings, inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an automated warehousing systemincluding the inventive vehicle position determining system;

FIG. 2 is a detailed perspective view of the transfer vehicle and robotvehicle of the warehousing system including the inventive vehicleposition determining system;

FIG. 3 is a schematic plan view of a robot vehicle, including theinventive vehicle determining system, proximate to a loaded pallet in awarehouse;

FIG. 4A is a detailed plan view of the flexibly mounted sensor system ofthe invention;

FIG. 4B is a detailed perspective view of the flexible mounting memberillustrated in FIG. 4A;

FIG. 4C is an end view of the clamp shown in FIG. 4A;

FIG. 4D is a top view of the clamp shown in FIG. 4A;

FIG. 5A is a plan view of the inventive reflector mounting bracket ofthe instant invention;

FIG. 5B is a top view of the bracket illustrated in FIG. 5A; and

FIG. 6 is a plan view of the scanner mounting plate of the instantinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, FIG. 1 illustrates a conventional warehousingsystem featuring the automatic storage and retrieval of articles,indicated at 1, which articles are carried by pallets indicated at 3.The multi-tiered storage system illustrated is formed by a number ofvertical structural members of beams 5 which combine with pairs ofhorizontal rails 7 (which rails function as tracks) to form lanes 9,three levels of such lanes 9 being illustrated in FIG. 1. A number ofvertical members or beams 11 generally comparable to those indicated at5, are provided, as are a number of pairs of horizontal rail or trackmember 13, the horizontal rail members 13 being generally comparable tothose illustrated at 7. The beams 11 and the tracks 13 combine to formthe aisles 15 of the warehousing system and, although only one aisle isillustrated in FIG. 1, it will be understood that a number of aisles 15are associated with each level of the lanes 9.

As is well known in the art (a typical system being illustrated in U.S.Pat. No. 3,973,685), such systems conventionally include mother vehiclesarranged to move along the tracks 7 of the lane 9, such a mother vehicleor transfer vehicle being indicated at 17. The transfer vehicle 17 isarranged to carry a satellite or robot vehicle indicated at 19, to aselected aisle 15 whereupon the robot leaves the mother vehicle andtravels to a desired position in such aisle where it deposits orretrieves a loaded pallet 3. As will readily be understood, it isnecessary that the warehouse system controller, for example, a computer(not shown), be apprised both of the fact that the transfer vehicle isproximate to the selected aisle (the aisle at which the vehicle 17 is tobe parked) and of the fact that the robot vehicle has arrived at aposition adjacent to, or in alignment with, the pallet nearest to thelane in an aisle, hereinafter referred to as "the first pallet". It isto provide such information that the instant photo-electric sensorsystem is provided. It is here noted that although, as just indicated,it is the warehouse system controller which must be informed of thelocation of the transfer vehicle and the location of the robot vehicle,for purposes of clarity the system will be discussed below in terms ofthe robot vehicle and transfer vehicle being apprised of theirrespective locations. Referring to FIGS. 2-4D the system providinginformation as to robot position will now be discussed in detail. Aspreviously noted, the robot vehicle 19 will be discharged from thetransfer vehicle 17 in an unloaded condition when it is desired toretrieve a pallet 3 from an aisle 15. Conversely, the robot vehicle willbe discharged in a loaded condition when it is desired to store a pallet3 in an aisle 15. In either event, it is necessary that the robotvehicle 19 be aware of its position in an aisle relative to the "first"loaded pallet therein. For example, if the robot vehicle 19 has beendischarged from the transfer vehicle 17 for the purpose of retrieving aloaded pallet 3, the robot vehicle must stop when it is under such"first" loaded pallet so that the pallet may be retrieved. If the robotvehicle is to deposit a loaded pallet in the aisle then the robotvehicle must sense when its leading edge is adjacent to the first palletin the aisle so that it may stop and deposit the pallet it is carryingadjacent to the previously first pallet in the aisle. To accomplish thistask two separate photo-electric transceivers have conventionally beenprovided, such transceivers being indicated at 31 and 33. Thetransceiver 31 functions when the robot is moving in the directionindicated by the arrow 34 to locate the leading edge of the first loadedpallet already in the aisle when it is desired that the robot vehicle 19deposit a pallet in the aisle and the photo-electric transceiver 33 isutilized when it is desired to retrieve the first loaded pallet in theaisle. At this point it is appropriate to note that although thewarehousing system illustrated in FIG. 1 shows aisles 15 extending inonly one direction from the lanes 9, warehousing systems are frequentlyarranged so that aisles 15 extend in both directions from each of thelanes 9. It is for this reason that the robot vehicle 19 is illustratedas having four photo-electric transceivers mounted thereon. Thetransceivers indicated at 35 and 37 (FIG. 3) correspond to thetransceivers 31 and 33, respectively, and are utilized when the robotvehicle 19 is discharged from the transfer vehicle 17 in the directionillustrated by the dashed lines in FIG. 2 and indicated by the arrow 38in FIG. 3. The mode of operation of these photo-electric sensors isconventional in the art (see U.S. Pat. No. 3,973,685) and such operationwill therefore not be more fully discussed. As previously noted,however, the sensors of such systems are subject to breakage due totheir coming into contact with objects over-hanging or otherwisedepending from pallets in the aisles. It has therefore been foundadvantageous to resiliently mount each of the sensors 31 and 35 on therobot vehicle by means of a flexible structure 41, which structure isillustrated in detail in FIG. 4A.

The resilient sensor mounting structure 41, includes a tubular member 43which may be made of any relatively resilient material such as, forexample, a plastic. In particular, urethane has been found to be asuitable material. Coupled to the tubular member 43, or formed as aportion thereof, is a sensor retainer 45 which supports a photo-electrictransceiver (transmitter and receiver combination) here indicated as thetransceiver 31. The retainer 45 may advantageously be made of arelatively strong material such as aluminum or a plastic and theretainer 45 is fixedly connected to the tubular member 43 in anyconventional manner. The retainer 45 may, of course as indicated above,be formed as an integral portion of the flexible structure 41 in whichevent the retainer 45 is made of a strong resilient material such asurethane as is the remainder of the mounting structure 41. The tubularmember 43, which is illustrated in detail in FIG. 4B, is formed withchamfered edges 47 so as to prevent damage to electrical cables 49 whichcouple the sensor 31 to a receiving unit (not shown) and which passthrough the interior passage 51 of the tubular member 43. The tubularmember 43 is slideably coupled to the robot vehicle 19 by a clamp 61. Asillustrated, the clamp 61 includes an upper portion 61a and a lowerportion 61b, each portion being formed with a semi-circular groovetherein, which grooves are adapted to surround and grip the tubularmember 43. The upper and lower clamp sections 61a and 61b, are urgedtogether by means of screws indicated at 63 and the clamp unit 61 isfixedly connected to any convenient interior portion of the robotvehicle 19, for example, a portion denominated as 19a by screws 65.Referring briefly to FIGS. 2 and 3, it is seen that the sensor retainer45 and a portion of the flexible tube 43 extend beyond the fore and aftends of the robot vehicle 19, the remainder of the tubular member 43 andthe clamp 61 being located within the interior of the robot vehicle 19.The just described structure coupling the tubular member 43 to the robot19 renders the flexible rod 43 and, of course, the sensor 31, slideablymoveable longitudinally relative to the robot vehicle 19. In this mannerthe distance that the sensors extend beyond the forward and rear ends ofthe robot vehicle may be selectively varied and this, in turn, permitsthe time between when a pallet is sensed and the time when the body ofthe robot vehicle arrives at the sensed pallet to be selectively varied.It will, of course, be understood that the resiliency of the tubularmember 41 prevents damage to, and misalignment of, the photo-electricsensors 31 in the event that the sensor retainer 45 contacts anobstruction, such as a piece of lumber, in an aisle and that the sensor,within the retainer, will simply return to its correct position, aftersuch obstruction has been removed.

As previously noted, it is not only necessary that the robot vehicle 19be aware of its position relative to the "first" pallet in an aisle butit is also necessary that the transfer vehicle 17 be aware of itsposition relative to each aisle as it moves along the tracks 7 of a lane9. To accomplish this end a photo-electric transceiver network,indicated generally at 71, is mounted on the transfer vehicle 17 bymeans of a transceiver mounting bracket or plate indicated at 73, whichmounting bracket is illustrated in detail in FIG. 6. Mounted adjacent toeach aisle 15, on, for example, a stanchion, (not shown) or on eachvertical beam 5, is a photo-electric reflector mounting bracket 81 whichis illustrated in detail in FIGS. 5A and 5B. It is here appropriate toindicate that, although the reflector bracket 81 is illustrated in FIG.1 as being mounted on the vertical beams 5 (facing inwardly) so as to beproximate to an aisle 15 to be identified, it will be clear that thereflector mounting bracket 81 may be mounted in a location and a mannerother than that discussed above, the only requirement being that thebracket be so located as to be able to identify an aisle. Turning firstto a discussion of the reflector mounting bracket 81 and referring toFIGS. 5A and 5B, it is noted that the bracket may be made of anyconventional material such as, for example, sheet metal. As seen mostclearly in FIG. 5B, the bracket 81 has a generally "C" shapedcross-sectional configuration. The bracket includes a longitudinallyextending rear wall 83 and first and second side walls 85 and 87, eachof which side walls extend perpendicularly from the same surface andfrom a respective end of the rear wall 83. The bracket 81 furtherincludes first and second pluralities of fingers, 89 and 91, whichextend from the side walls 85 and 87, respectively. The pluralities offingers 89 and 91 both extend inwardly, that is, toward one another, andboth pluralities extend parallel to the rear wall 83. The combination ofthe rear wall 83, the side walls 85 and 87, and the fingers 89 and 91thus provides a structure which forms a channel into which reflectorsmay be placed and which is therefore suitable for use as a retainingmember.

Referring to FIG. 5A, it may be seen that each finger of the twopluralities of fingers 89 and 91 is independent of each other finger. Itwill therefore be understood that each finger may be separately foldedinward toward the wall 83, as indicated by the dashed lines in FIG. 5Band in this manner provide support for a photo-electric reflector. Thus,a photo-electric reflector may be maintained in any position by foldingthe finger pair next adjacent to such position inwardly toward the rearwall 83. It is here noted that although a single inwardly folded fingeris sufficient to maintain a reflector, superior support may be providedby inwardly folding two corresponding (facing) fingers, i.e., one of thefingers 89 and the finger 91 corresponding thereto. It will beunderstood, of course, that if it is desired to maintain a reflector ina particular position then the finger pair 89-91 of that position willnot be folded inwardly as indicated by the dashed lines in FIG. 5B, butrather, will be in the position there shown in solid lines.

The embodiment of the bracket 81 illustrated in FIG. 5A is structured toprovide six positions for reflectors which are arranged in a patterncontaining location information, that is, are arranged in a code. Thesesix positions are indicated at A-F. The location information may, forexample, be contained in a simple binary code where position A is theposition of the least significant digit. Thus, if a single reflector isat position A, the transceiver 71 is arranged to provide an outputsignal indicating that the transfer vehicle 17 is at the first of theaisles. Similarly, if reflectors are in positions A and D, then thetransceiver 71 will provide an output signal indicating that thetransfer vehicle is at the ninth of the aisles 15. The reflectorposition adjacent to position A, which adjacent position is indicated atG, is aligned with fingers 89a and 91a which are similar to the fingers89 and 91. The fingers 89a and 91a are distinguished from the fingers 89and 91 in that the former extend a greater distance toward one anotherthan do the fingers 89 and 91. The purpose of this structure of thefingers 89a and 91a is to enable them to cover a greater portion of thereflector which will be located in position G than is the case withrespect to the reflectors positioned in the locations A-F. The reasonwhy it is desired that a greater portion of the reflector in location Gbe covered, that is, that the reflector have a lesser reflectiveexpanse, will be discussed in detail below. The reflector position nextadjacent to position G is indicated at H and this position is utilizedfor the fine positioning of the transfer vehicle 17 in a manner whichwill be discussed below. It will be noted that the two outermostreflector positions of the retainer 81, indicated at J and K, do notextend as great a distance, in a longitudinal direction, as do thereflector positions A-H. In point of fact, the positions J and K eachhave a longitudinal extent approximately one-half of that of theremaining reflector positions and this is due to the fact that thepositions J and K are utilized only when the code is such that twophoto-electric reflector retainers 81 are to be coupled together. Insuch event the J position of the first retainer 81 will be adjacent tothe K position of the second retainer 81 thereby forming a fullreflector position, i.e., a position adapted to receive a reflectorcomparable to the reflectors which may be placed in positions A-H.

A pair of slots, indicated at 93 and 95, are formed in the retainer 81and these slots are arranged to receive coupling members (not shown) forconnecting the retainers 81 to the beams 5 (or other support members).For example, screws may be utilized to connect the retaining members 81to the beams 5 or clips may be used for this purpose. The slots 93 and95 are arranged to extend transversely relative to the longitudinalextent of the retaining member 81 so that the retaining member may bemoved in the transverse direction for purposes of adjustment.

It will be understood that many different types of reflectors may beutilized in the instant invention, the type of reflector selecteddepending in part on the sensing means selected. However, the type ofreflector advantageously utilized with the photo-electric sensing meanshere described is a conventional motor truck type of reflector commonlyknown as a "corner cube" which, as is well known, has a smooth exposedsurface and a faceted rear mounting surface. Such reflectors are herepreferred because it is a characteristic of such reflectors that theyreflect any light received back in the direction from which it istransmitted, even when such light is not transmitted perpendicularly totheir receiving face. Although, as previously noted, other types ofreflectors, for example, reflective tape, could here be utilized, it hasbeen found that the corner-cube reflectors are superior for a number ofreasons in addition to their ability to reflect light on the line oftransmission. For example, the reflective surface of a corner-cubereflector does not become grimy, with a concommitant loss ofreflectivity as quickly as does tape. Further, a corner-cube reflectormay be more readily and thoroughly cleaned by merely wiping it with adamp cloth than can a tape. Finally, the position of the reflectors in aretainer can be more readily changed, thereby changing the informationcontained in the reflector pattern, than is true of reflective tapeswhich must be peeled from a mounting stanchion and repositioned (with aloss of adhesiveness) when it is desired to change the informationcontained in the tape pattern.

The transceiver mounting bracket 73 is illustrated in detail in FIG. 6and it is utilized to attach the photo-electric transceiver or scanner71 to the vertical portion of the transfer vehicle 17, which verticalportion is indicated at 17a. The individual photo-electric transceivers,which together form the transceiver or scanner 71, are conventional andof the type which include a lens system adapted to both transmit andreceive light. In addition, the body or casing of the transceiverincludes an alignment pin spaced from the lens, which alignment pinextends parallel to the axis of transmission of the lens, and the casingis formed with a threaded aperture which is adapted to receive amounting screw. Although the structure and operation of the individualtransceivers is conventional and will therefore not further bediscussed, the mounting bracket for, and the arrangement of, theconventional transceivers is part of the instant invention and thebracket and arrangement therefore will be discussed in detail. Thetransceiver bracket 73 may be made of any conventional material such as,for example, sheet metal and it is formed with a plurality of circularapertures therein. There are three sizes of such circular apertures andthe largest of the apertures are indicated at 101, 103, 107, 109, 111and 113. The apertures 101-113 are provided so that the lenses of theindividual photo-electric transceivers, which are positioned at the rearof the mounting bracket 73, may be aligned with and transmit and receivelight therethrough. Adjacent to the largest circular apertures 101-113are smaller circular apertures indicated at 101a-113a, the latterapertures being aligned transversely with the apertures 101-113. Theapertures 101a-113a are so located in the bracket 73 that each may bealigned with the threaded aperture in the transceiver casingcorresponding thereto. Mounting means, such as, for example, screws, maythus pass through the apertures 101a-113a and into the correspondingthreaded apertures in the transceivers whereby the individualtransceivers may be attached to the bracket 73. Located adjacent to theapertures 101a-113a, and transversely aligned therewith, are thesmallest apertures, indicated at 101b-113b. The purpose of the apertures101b-113b is to receive the transceiver casing alignment pins andthereby insure the alignment of each of the transceiver lenses with thecorresponding aperture 101-113. Formed in the bracket 73 are fourcircular apertures, indicated at 120, which circular apertures arearranged to receive shock suppressing devices, for example, rubbergrommets, which serve to isolate the photo-electric transceiver mountingbracket 73 (and the transceiver 71) from the vibration of the transfervehicle 17.

As will readily be understood, the photo-electric transceiver means 71is mounted, via the bracket 73, so that it will come into alignment withthe reflectors (A-H) positioned in the reflector mounting structure 81as the transfer vehicle 17 moves along the lane 9. It is appropriate tonote at this time that, although in the embodiment illustrated both thereflector bracket 81 and the transceiver mounting bracket 73 arevertically oriented, comparable results may be obtained, with only minorobvious modifications, if both the transceiver support bracket 73 andthe reflector mounting bracket 81 are horizontally oriented. Returningnow to the embodiment illustrated, it will be understood that theindividual photo-electric transceivers 103-113 (each discretephoto-electric transceiver being identified by the numeral indicatingthe aperture with which such transceiver lens is aligned) are arrangedand spaced so as to be aligned with the reflectors A-F, respectively, asthe transceiver 71 moves into vertical alignment with the reflectormounting bracket 81. Thus, the transceiver 103 responds to thereflection from a reflector in position A and the transceiver 111responds to the reflection from a reflector in position E. Thetransceiver 71 mounted in the bracket 73 is therefore able to provide anoutput signal (which can be decoded in any conventional manner) which isrelated to the location information containing pattern or code of thereflectors A-F.

As has just been noted, the transceivers 103-113 correspond to, i.e.,are aligned with, the reflector positions A-F. It will therefore beunderstood that the transceiver 101 will be aligned with the reflectorat location G in the mounting bracket 81. The reason that the fingers89a and 91a are arranged to extend somewhat further toward one anotherthan do the remainder of the fingers 89 and 91 will now be discussed. Itwill be seen that, as the transceiver 71, mounted on the verticalportion 17a of the transfer vehicle 17, moves into alignment with thereflectors mounted on the reflector mount 81, the discrete transceiver101 will receive a reflection from the reflector at location G after theremaining transceivers (103-113) receive reflections from the reflectorsA-F. This is because the fingers 89a and 91a, which are constructed fromthe same non-reflective material as the remainder of the retainingmember 81, prevent reflection. The transceiver 101 will therefore haveto be more nearly aligned with the center of the reflector G, before areflected photo-electric signal is received, than would be the case ifthe fingers 89a and 91a extended toward one another only as far as thefingers 89 and 91. The combination of the transceiver 101 and thefingers 89a and 91a is therefore particularly suitable for use as aswitch initiating the operation of the transceivers 103-113. This isbecause the use of such a switching control prevents the activation, forthe transmission and reception of photo-electric signals, of thetransceivers 103-113 before they are properly aligned with thereflectors in positions A-F and the possibility of spurious readings,which could occur if the transceivers 103-113 responded to the leadingand trailing edges of the reflectors A-F, is therefore minimized.

As illustrated in FIG. 6, three transversely extending slots, indicatedat 121, 123, and 125, are formed in the mounting plate 73, these slotsbeing provided for receiving two discrete photo-electric transceivers.The slot 125 corresponds generally to the circular apertures 101b-113bin that the slot 125 is adapted to receive the transceiver alignmentpins of the two transceivers. The slot 123 corresponds generally to thecircular apertures 101a-113a in that the slot 123 is adapted to receivethe threaded screws for mounting the two transceivers to the plate 73.The slot 121 corresponds generally to the circular apertures 101-113 inthat the slot 121 is adapted to receive, or be aligned with, the lensesof the two transceivers. The two photo-electric transceivers arearranged to be individually moveable along the longitudinal axes of theslots. Thus, either or both transceivers may be moved to the left or tothe right and they can be moved toward one another or away from oneanother. This arrangement of the pair of photo-electric transceivers,the lenses of which are aligned with the slot 121, functions as a finealignment mechanism. Referring to FIGS. 5A and 6, it will be seen thatthe slot 121 is aligned with a reflector in the position H of thebracket 81. By controlling the movement of a transfer vehicle 17 whichis already near an aisle 15 so that the vehicle jogs to and fro untilboth of the transceivers 121 receive reflections from the reflector H,the position of the transfer vehicle relative to the aisle 15 may befinely controlled. In point of fact, the precision with which theposition of the transfer vehicle 17 is controlled is dependent upon thespacing between the two transceivers 121. Thus, if the two transceivers121 are spaced relatively closely together, they will both receivereflections from the reflector H although the vehicle 17 is rathercoarsely aligned with an aisle 15. On the other hand, when the twotransceivers 121 are spaced relatively far apart, the alignment of thevehicle 17 with an aisle 15 will, of necessity, be relatively moreprecise if the transceivers 121 are able to simultaneously receivereflections from the reflector in position H. It is therefore seen thatthe just described fine alignment arrangement is suitable for preciselyaligning a vehicle 17 with an aisle 15 and that it further is anarrangement which permits control of the degree of such precision ofalignment.

Although the invention system has here been described in terms ofphoto-electric transceivers, the instant system could also be utilizedwith other forms of energy which can be reflected such as, for example,infra-red radiation, magnetism, etc., and the subject system maytherefore be referred to as an electro-magnetic or electro-optical wavesystem, rather than merely as a photo-electric system.

It will be understood that the foregoing description of the preferredembodiment of the present invention is for purposes of illustration onlyand that the various structural and operational features as hereindisclosed are susceptible to a number of modifications and changes, noneof which entail any departure from the spirit and scope of the presentinvention as defined in the hereto appended claims.

What is claimed is:
 1. A reflector retaining bracket comprising:alongitudinally extending rear wall; first and second side walls, saidside walls being spaced from one another and extending perpendicularfrom a surface of said rear wall; and first and second pluralities offingers, each of said first and second pluralities of fingers extendingperpendicularly from a corresponding one of said first and second sidewalls and toward one another, said rear and side walls and saidpluralities of fingers forming a channel adapted to maintain a pluralityof reflectors therein, each of said fingers being adapted to be foldedinwardly toward said rear wall for preventing the longitudinal movement,toward said folded finger, of a reflector positioned in that portion ofsaid channel aligned with the fingers next adjacent to said foldedfinger.
 2. A reflector retaining bracket according to claim 1 whereineach finger of said first plurality of fingers is aligned transversly,with respect to said longitudinal direction, with a corresponding fingerof said second plurality of fingers.
 3. A reflector retaining bracketaccording to claim 2 wherein a selected finger of said first pluralityand the corresponding finger of said second plurality each extend agreater distance toward one another then do the remaining fingers ofsaid first and second pluralities of fingers.
 4. A reflector retainingbracket comprising:a vertically oriented longitudinally extending rearwall; first and second side walls, said side walls being spaced from oneanother and extending perpendicularly from a surface of said rear wall;and first and second pluralities of fingers, each of said first andsecond pluralities of fingers extending perpendicularly from acorresponding one of said first and second side walls and toward oneanother, said rear and side walls and said pluralities of fingersforming a channel adapted to maintain a plurality of vertically arrayedreflectors therein, each of said fingers being adapted to be foldedinwardly toward said rear wall so that the space between said fingersand said rear wall is less than the thickness of said reflectors wherebythe lower edge of a reflector is supported by a pair of fingers therebypreventing the longitudinal movement, in the direction of said foldedfingers, of a reflector positioned in that portion of said channelaligned with the fingers next adjacent to said folded fingers.